In a study of more than 1000 hospitals in the U.S. reported in the Pharmacotherapy Journal in 2001, medication errors occurred in 5.07% of the patients admitted and 0.25% of the patients were seriously injured. On the average, each hospital committed one medication error every 22.7 hours. According to a report published by the American Institute of Medicine in 2006, the total cost for medication errors is more than $3.5 Billion/year, but this estimate does not include the cost for extended care. In a study of 36 hospitals and nursing homes in Colorado and Georgia reported in the Archives of Internal Medicine in September 2003, the most common drug error is giving hospitalized patients their medications at the wrong times or not at all. In 2001, the American Association of Critical-Care Nurses reported that distractions cause 36% of the reported medication errors in the U.S.
Many patents have been issued for devices that automatically dispense pills, such as U.S. Pat. No. 5,405,011 issued to Haber, et al. in April 1995, U.S. Pat. No. 5,575,392 issued to Cutler in November 1996, U.S. Pat. No. 5,641,091 issued to Daneshvar in June 1997, and U.S. Pat. No. 5,609,268 issued to Shaw in March 1997. None of these inventions use RFID tags or barcode labels to identify the medication or the patient.
U.S. Pat. No. 5,700,998 issued to Palti in December 1997, describes a simple concept of printing a linear or radial barcode label directly onto each pill. In another noteworthy invention, U.S. Pat. No. 5,564,803 issued to McDonald, et al. in October 1996 describes a “portable nursing center” attached to a cart with wheels. The data entry is via a keypad, barcode reader or touch screen; therefore, both the patient and the medications can be identified via barcode labels. The cart contains drawers that automatically open to access pills for an identified patient, and the cart computer also provides access to patient records. Some hospitals like this method for delivering medications, but it assigns most of the delivery workload to nurses, and the nurses are already overworked and understaffed. Furthermore, infectious organisms can be easily carried from room to room via the cart.
Some hospitals believe it is more cost effective to store medications inside stationary locked cabinets at central locations, such as one cabinet on each nurses' station, floor or wing of a hospital. U.S. Pat. No. 5,405,048 issued to Rogers, et al. in April 1995 describes a medication storage cabinet with separate compartments for pills and a vacuum operated mechanism for individually dispensing pills into a cup. U.S. Pat. No. 5,883,806 issued to Meador, et al. in March 1999 describes a large drug dispensing cabinet with drawers that automatically open when a request is input via a keyboard. U.S. Pat. No. 6,975,922 issued to Duncan, et al. in May 2003 describes an instrumented cabinet with bins and a variety of drawers which contain supplies that could include medications. The configuration of the cabinet proposed by Duncan, et al. is not appropriate for a hallway in a large hospital, but it would be appropriate for a supply cabinet at a nurses' station. A computer guides the worker in finding each requested item by turning on a light at the location in the cabinet where the item is stored. The light does not blink to indicate the number of medications needed for a pillbox.
Most prescribed medications in hospitals are administered at standard times; therefore, the line at a central medication cabinet can get very long just before the standard medication times each day and evening. More important, this delivery scheme requires each nurse to collect all of the medications for several patients at the same time, which could add up to more than 50 medications. Missing pills and other medication errors are more likely to occur in this delivery scheme, but pharmacy workers like the idea of refilling a small number of locked cabinets in the hospital each day. It is important to remember that nurses are making the vast majority of the medication errors occurring in hospitals and nursing homes, and they need help.
A point-of-care computer system is described in U.S. Pat. No. 7,154,397 issued to Zerhan, et al. in December 2006. The point-of-care computer and other electronics are contained inside a bedside frame. The computer controls bed motors, provides access to patient records, and receives data from diagnostic, treatment, and therapy devices. The point-of-care computer also interfaces with a barcode, RFID or other readers for identifying the patient, attendants and medications. When a caregiver brings a “locked medical box” to the patient's room, the patient and medications are scanned by the attendant to verify that the medications match the pharmacy records for the patient. The locked medical box can be attached to different described carts.
Most nurses like the concept of a medication workstation close to each patient room, but there are several problems with the Zerhan invention. If medications and medical supplies are kept inside the patient room, infectious organisms could be easily passed on to the next patient via the storage cabinet. Also, pharmacy workers would not like the idea of delivering a “locked medical box” to a workstation inside each patient room. The rooms could be congested or inaccessible, and any medical boxes left in the hallway could be stolen. If nurses deliver each medical box via a cart or other means, they would be reverting to the delivery methods described in the McDonald patent of 1996, except there would be a separate locked medical box for each patient. The additional workload for nurses would be unacceptable to nursing supervisors.
Several of the above inventions mention RFID tags as an alternative to barcode labels and RFID is an important part of my invention. Passive RFID tags can be used to identify medication containers, supplies, equipment, patients and staff in hospitals. The recent shift from barcode to passive RFID is mostly driven by the fact that RFID transceivers operating at 13.56 MHz and higher frequencies are able to read a large number of tags at the same time, plus the additional advantage that a high-power RFID antenna can be located several feet away from an identified passive tag. If the RFID tag is active (i.e. powered by a battery), the distance between the antenna and the identified tag can be more than 10 feet. It is important to realize that any RFID tag can be easily shielded by wrapping aluminum foil around the tag; therefore RFID tags will never replace barcode readers at the checkout counter in Wal-Mart® stores. For the same reason, it is unlikely that RFID tags will be 100% effective in preventing theft of equipment, medications or babies in hospitals.
Another important limitation of RFID is related to the frequencies of the RF signals transmitted and received by RFID antennas. Higher frequency RFID systems can read a large number of tags at the same time via frequency hopping and other schemes. But at higher frequencies, the smaller wavelengths are not able to go through or around large conductive objects. For example, metal shelves, carts and human bodies can easily block passive RFID readers designed to operate at 2.4 GHz; therefore line of sight communications may be required between a high-frequency RFID antenna and matching tags. RFID signals at 134 KHz are better able to pass around human bodies, but 134 KHz readers are easily jammed by multiple tags.
At some time in the near future, the pharmaceutical industry will hopefully offer wrapped pills with RFID tags instead of barcode labels. More information can be written on an RFID tag, including secret codes that identify the pharmaceutical companies. The latter feature will help prevent counterfeit drugs. U.S. Pat. No. 7,156,305 issued to Swan, et al. in January 2007 presents several novel concepts related to RFID tags on medication containers, e.g. identifying counterfeit drugs, improper return of a medication, and supply chain abuses.
U.S. Pat. No. 7,091,864 issued to Veitch, et al. in August 2006 describes a research application of attaching a large number of RFID tags to containers in pharmaceutical studies. In this application, details about each specimen are written on the RFID tag. This invention is not a system for monitoring patients, pillboxes or equipment in healthcare facilities, and hospitals would not like the concept of fabricating custom RFID tags for each patient.
U.S. Pat. No. 7,175,081 issued to Andreasson, et al. in February 2007 describes how a large number of medications with an RFID tag on each medication can be quickly identified using an RFID reader inside a locked “medication-dispensing unit” to determine which medications have been removed from the cabinet and when one of the medications needs to be replenished. Access to the locked cabinet requires the healthcare worker to be identified via an electronic card, PIN or RFID tag. It is then possible to identify if the worker has removed the correct medications for an identified patient or when a pharmacy worker has placed an incorrect medication in one of the compartments inside the cabinet.
Unfortunately, there is a limit to the number of passive RFID tags that can be read at the same time. The current state of the art limits the number of passive RFID tags to a number much smaller than the typical number of medications stored in a medication-dispensing unit on each floor of a hospital. The above inventors solved this problem by providing a separate RFID antenna for each compartment inside the cabinet. This approach requires a large number of RFID antennas and associated equipment.